Playing CounterStrike myself regurlarly and being on a LAN with a few professional P2Pers, I had the same problem and also experienced the non-stable pings. At first I started experimenting with the rates and ceilings, but in practice that didn't help much. (one of) the reasons for the unstable ping is that a packet of ~ 1500 bytes on a 128kbit connection (like yours and mine) takes roughly a 10th of a second to send (100ms). So at the moment a large packet is being sent and a quake packet is next in the queue, it still has to wait 100ms (worst case). This latency of course adds to the normal latency you already have to the quake server. What does seem to help a little is lowering the maximum packet size (MTU) in your routing table: #!/bin/sh oldroute=`ip route | grep default | cut -d' ' -f-5` ip route change $oldroute mtu 500 The cut takes care of removing the 'mtu xxx' from a line like this (type "ip route": to see it) default via a.b.c.d dev eth0 mtu 900 It only takes the first 5 words. I presume that number of words can be different in other situations, so you might have to adapt for that. (or use something other than 'cut' to do it properly). Note that the MTU only effects the outgoing packetsize, so downloads are not affected at all. Uploads do get a little less efficient (the packetheaders consist of a larger portion of the traffic) but in practise this is still acceptable. Game packets are pretty small anyway, so won't be affected at all. I'm assuming the burst and quantum settings can be optimized for smaller packet sizes to take full advantage of this. But to be honest I haven't really done that yet. I use a cable connection which has a more than 10 times faster download than upload, so for me shaping the download isn't very effective. If you want to limit the maximum packetsize for incoming packets as well (at least for TCP) you can simply do this: iptables -I PREROUTING -t mangle -i eth0 -j TCPMSS --set-mss 1000 -p TCP --tcp-flags SYN,RST SYN iptables -I INPUT -t mangle -i eth0 -j TCPMSS --set-mss 1000 -p TCP --tcp-flags SYN,RST SYN For 1000 bytes packets. You can also use --clamp-mss-to-mtu option, which probably makes sense. Note that the MSS thing only works for new connections. Note: After you change the MSS value, existing connections will still use the old size. MTU changes have effect immediately. Also make sure you patched the kernel to use the high resolution timer (info at www.docum.org somewhere). That helped a lot in my case (you can put the ceilingrates closer to the actual 128kbit and therefore reduce latency as well). I'm not sure it's still necessary on 2.4.20 and/or 2.4.21. Jannes Faber ----- Original Message ----- From: "Thilo Schulz" <arny@xxxxxxxxxxxxxx> To: <lartc@xxxxxxxxxxxxxxx> Sent: Saturday, June 14, 2003 5:54 PM Subject: [LARTC] Low latency on large uploads - almost done but not quite. Does anyone of you have an idea how I can minimize this effect, and let pings be stable at 60 ms? stable 80ms delay are okay for me too, no question. If I let the worst-priority bulkdownload class ceil up only to 10kbyte/s I have the same effect, only when the max ceil class is put down under 6 i do not have this changing ping effect.
